The objective of the proposed research is to identify the psychobiological origins of the Type A behavior pattern, which is a major risk factor for coronary heart disease. To achieve this goal, demographic, psychosocial, and cardiovascular risk factors will be examined in relation to the emergence and stabilization across time of the Type A behavior pattern and its component characteristics. Approximately 1800 children and young adolescents residing in Pittsburgh, Minneapolis, and Bogalusa, Louisiana will be studied in a three-year longitudinal-cohort design after completion of psychometric work on the Matthews Youth Test for Health during the first year. This scale is relatively well developed and yields scores for overall Pattern A and its component characteristics. Among the specific data to be collected on groups of children are the following: static measures of blood pressure, heart rate, and serum cholesterol; dynamic measures of children's cardiovascualr reactions to environmental challenge; and parents' perceptions of children's activities and recent life changes. The proposed research potentially can aid in (a) understanding the origins of adult behavior pattern which may lead to further refinements in the definition of Pattern A, (b) identifying the age when psychobiological parallels of children and adults exhibiting Type A behaviors emerge. (c) predicting the adult behavior pattern, and (d) eventually knowing how and when to most effectively modify Pattern A.